Machine qf Ctesibim.
267
Chap. 3.]
tors and commentators have generally agreed in their views of it as re-presented below, viz : two ordinary forcing pumps connected to an air~vessel and one discharging pipe.
fnllil
WM
WM
The cylinders are secured in a frame of timber, and the piston rods areattached by joints to levers, one end of which are depressed by cams onthe axis of the wheel, as shown above and also at No. 89. Barbaro hasfigured a crank at the axis which gives a reciprocating motion to a hori-zontal shaft placed over the pumps, and projecting pieces from which impartmotion to the piston rods. Yitruvius informs us that when machines wereemployed to raise water from rivers, they were worked by undershotwheels impelled by the stream, and hence the pumps of Ctesibius werebelieved to have been moved by the 'same means.
But for Vitruvius we should not have known that forcing pumps con-stituted part of the water Works of antiquity ; and had he not remarkedthat they were employed to supply “ public fountains,” it might have beensupposed that water never rose higher in the dwellings of ancient citiesthan that which was drawn directly from the aqueducts.
It would be almost unpardonable to pass over this celebrated machinewithout further remark, since it is, in several respects, one of the mostmteresting of all antiquity. An account of its origin and early historywould form a commen tary on most of the arts and Sciences of the ancients,and would, we believe, furnish evidence of their progress m some of themthat few are willing to believe. Although it was attributed to Ctesibius ,there is some uncertainty respecting the extent of his Claims. It may ap-pear invidious to attempt to rob this illustrious man of inventions ascribedto him, but our object is to ascertain, not to depreciate them or diminish